Prevalence of Diarrhea and Enteropathogens in Racing Sled Dogs     

E. McKenzie  J. Riehl  H. Banse  P.H. Kass  S. Nelson  Jr  S.L. Marks 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2010,24(1):97-103

Background: Diarrhea is highly prevalent in racing sled dogs, although the underlying causes are poorly understood.
Hypothesis: Clostridium perfringens enterotoxin (CPE) and Clostridium difficile Toxin A and B are associated with diarrhea in racing sled dogs.
Animals: One hundred and thirty-five sled dogs.
Methods: Freshly voided feces were obtained from 55 dogs before racing and from 80 dogs after 400 miles of racing. Samples were visually scored for diarrhea, mucus, blood, and melena. CPE and C. difficile Toxin A and B were detected by ELISA. Samples were cultured for C. perfringens, C. difficile, Campylobacter, Salmonella , and Escherichia coli 0157; Giardia and Cryptosporidium spp. were detected via immunofluorescence.
Results: Diarrhea occurred in 36% of dogs during racing, and hematochezia, fecal mucus or melena, or all 3 occurred in 57.5% of dogs. Salmonella was isolated from 78.2% of dogs before racing, and from 71.3% of dogs during racing. C. perfringens and C. difficile were isolated from 100 and 58.2% of dogs before racing, and from 95 and 36.3% of dogs during racing. Dogs were more likely to test positive for CPE during than before racing (18.8 versus 5.5%, P = .021); however, no enteropathogens or their respective toxins were significantly associated with hematochezia or diarrhea.
Conclusions and Clinical Importance: Sled dogs participating in long distance racing have a high prevalence of diarrhea and hematochezia that is not associated with common enteropathogens. It is possible that diarrhea and hematochezia represent the effect of prolonged exercise on the gastrointestinal tract.  相似文献   

Importance of Limestone Specific Surface for Assessing Neutralization Effectiveness in Soilless Root Substrate     

Janet F. M. Rippy  Paul V. Nelson  Dean L. Hesterberg  Eugene J. Kamprath  Ted Bilderback 《Communications in Soil Science and Plant Analysis》2016,47(4):521-526

The relationship of specific surface to particle diameter and calcium carbonate (CaCO₃) content of limestone was examined. Limestones obtained from 20 North American quarries were wet sieved into eight particle diameter fractions (600 to ?38 µm). Specific surface of particles was measured in each fraction following the Brunauer-Emmett-Teller theory. The range in specific surface across the 20 sources varied from 74-fold in the coarsest particles (600–300 µm) to 20-fold in the finest particles (?38 µm). The pattern of specific surface progressing from the coarsest to the finest particles varied radically between sources. The relationship between specific surface and CaCO₃ content was likewise very weak. While particle diameter and CaCO₃ equivalent remain the traditional measurements for defining limestone for field production, specific surface provides additional information valuable to define the stricter neutralization capacities of limestone for soilless root substrates.  相似文献   

Atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi     

Sebastian Elgueta  Cledir Santos  Nelson Lima 《Archives of Agronomy and Soil Science》2016,62(10):1451-1461

Due to environmental concerns about accumulation of the herbicide atrazine in food products and water reservoirs, there is a need to develop safe and economical methods for its dissipation. The main aim of this study was to evaluate atrazine dissipation in a biobed system inoculated with immobilized white-rot fungi in a pelletized support (PS). All fungal isolates evaluated were efficient in colonizing the surface and inner parts of the PS, with no differences observed in the colonization over the assay. The highest atrazine dissipation (93%) was observed for Stereum hirsutum Ru-104 after 60 days of incubation. In contrast, the lowest atrazine dissipation (78%) was observed for the non-inoculated biobed over an identical period. Trametes versicolor HL01 was involved in the highest phenoloxidase activity. This activity indicates that inoculated and non-inoculated biobeds were biologically active over the incubation period. A high respiration rate in the biobed was observed when it was inoculated with S. hirsutum Ru-104. Inoculation of fungi on PS systems may be a coadjutant in the increase of fungal efficiency in enzymatic production.  相似文献   

Participatory guarantee systems and the re-imagining of Mexico’s organic sector     

Erin Nelson  Laura Gómez Tovar  Elodie Gueguen  Sally Humphries  Karen Landman  Rita Schwentesius Rindermann 《Agriculture and Human Values》2016,33(2):373-388

Although it is the most widely accepted form of organic guarantee, third party certification can be inaccessible for small-scale producers and promotes a highly market-oriented vision of organics. By contrast, participatory guarantee systems (PGS) are based on principles of relationship-building, mutual learning, trust, context-specificity, local control, diversity, and collective action. This paper uses the case study of the Mexican Network of Local Organic Markets to explore how PGS can be used to support a more alternative vision of organics, grounded in the notion of food sovereignty. It presents some of the key challenges and opportunities associated with the approach, and highlights its potential to serve as a locally-based institution for collective action, thereby offering some structural support to alternative agri-food initiatives.  相似文献   

The activity of a selected extract of <Emphasis Type="Italic">Drimys winteri</Emphasis> bark and polygodial on settling and probing behavior of the lettuce aphid <Emphasis Type="Italic">Nasonovia ribisnigri</Emphasis>     

Nelson Zapata  Marisol Vargas  Pilar Medina  Elisa Viñuela  Benjamín Rodríguez  Alberto Fereres 《Phytoparasitica》2010,38(2):191-199

An n-hexane extract and the sesquiterpene polygodial isolated from the bark of Drimys winteri J.R. Forster & G. Forster (Winteraceae) were tested to assess their ability to inhibit settling of the aphid Nasonovia ribisnigri Mosley on lettuce leaves; assessments were made using a choice and no-choice leaf-disk assay. The n-hexane extract and the polygodial both significantly inhibited settling in the choice and no-choice tests, but their application on lettuce leaves did not result in any aphid mortality. Probing behavior of N. ribisnigri on polygodial-treated plants was assessed by means of the electrical penetration graph technique. Polygodial interfered with aphid probing behavior by reducing the total probing time, the number of probes, and the number of intracellular punctures. Aphids did not reach the sieve elements of polygodial-treated plants during the 2-h access period. Both tested compounds have the potential to be used in the development of lettuce aphid control agents to reduce the risk of virus transmission.  相似文献   

Biosorption of Toxic Metals by Water Lettuce (<Emphasis Type="Italic">Pistia stratiotes</Emphasis>) Biomass     

Ana Carolina Dornelas Rodrigues  Nelson Moura Brasil do Amaral Sobrinho  Fabiana Soares dos Santos  André Marques dos Santos  Ana Carolina Callegario Pereira  Erica Souto Abreu Lima 《Water, air, and soil pollution》2017,228(4):156

Adsorption isotherms were constructed to evaluate the potential use of water lettuce (Pistia stratiotes) dry biomass for the biosorption of zinc and cadmium. One gram of dry biomass of this plant was treated with five increasing doses of zinc (1.8, 18, 50, 79, and 105 mg L^?1) and four doses of cadmium (0.01, 0.1, 1, and 10 mg L^?1), for nine collection times (1, 3, 6, 12, 24, 36, 48, 60, and 72 h). The levels of these metals were determined by atomic absorption spectrophotometry. To evaluate changes in the surface morphology of the dry biomass, scanning electron microscopy (SEM) images were taken of the samples subjected to the greatest contamination, and these were compared with the images of the samples without zinc and cadmium (control). The ISOFIT software was used to select the isotherm model that best fit the biosorption of metals by water lettuce dry biomass. The linear model was determined to be the best-fitting isotherm model, because it had the lowest corrected Akaike information criterion (AICc) value and a Akaike weight (AICw) value closest to one, which indicates the high affinity of the biosorbent for the adsorbates evaluated. The results for both metals demonstrated greater than 70% reductions in the concentrations of the metals in the contaminated solutions. The SEM images indicated changes in the morphology of the contaminated biomass, thus demonstrating the biosorption mechanisms and confirming the potential of the dry biomass of this plant for use in the remediation of solutions contaminated with zinc and cadmium.  相似文献   

Demographic and preliminary employment data of the first two graduate cohorts from a rural veterinary school          下载免费PDF全文

JH Hyams  SL Raidal  LM Hayes  J Heller 《Australian veterinary journal》2017,95(4):91-100

  相似文献   

Economic and Risk Effects of Rotation Based on a 14-Year Irrigated Potato Production Study in Manitoba     

Mohammad Khakbazan  Ramona M. Mohr  Jianzhong Huang  Erik Campbell  Karl M. Volkmar  Dale J. Tomasiewicz  Alan P. Moulin  Doug A. Derksen  Byron R. Irvine  Debra L. McLaren  Alison Nelson 《American Journal of Potato Research》2018,95(3):258-271

Crop rotations can be used to optimize economic return by preserving or enhancing soil quality and reducing pest pressure. A field experiment consisting of six rotations of potato with canola (P-C), wheat (P-W), canola-wheat (P-C-W), oat-wheat (P-O-W), wheat-canola-wheat (P-W-C-W), and canola underseeded to alfalfa-alfalfa-alfalfa (P-C(A)-A-A) organized in a Randomized Complete Block Design was established on a clay loam soil in Manitoba, Canada and monitored for fourteen years to assess the relative economic performance of potato in each rotation. A stochastic budget based on returns and risk of returns trade-offs was used to determine each rotation’s profitability. While differences in average annual net income of all crops between rotations were not significant, the P-C-W rotation was the most stable. Despite the economic advantage of P-C in the first two cycles, longer P-C-W or P-C(A)-A-A rotations are recommended, as two-year rotations increase plant disease and decrease economic viability in the long run.  相似文献   

Institutionalizing agroecology: successes and challenges in Cuba     

Erin Nelson  Steffanie Scott  Judie Cukier  Ángel Leyva Galán 《Agriculture and Human Values》2009,26(3):233-243

Over the past two decades, Cuba has become a recognized global leader in sustainable agriculture. This paper explores how this process of agricultural transition has taken place, and argues that it has largely been led by research institutes, non-state organizations and the Cuban government, which have all contributed to the institutionalization of agroecology in both policy and practice. This process has been highly effective in terms of the numbers of people using agroecological techniques. However, although these techniques have been widely adopted by farmers across the country, this paper suggests that many still perceive maximizing production to be a higher priority than maintaining a commitment to agroecological ideals. For these farmers, agroecological farming is viewed primarily as a pragmatic decision rather than an ideological or moral one, and they may thus be susceptible to shifting back to conventional production if this option became politically and economically feasible

Steffanie Scott (Corresponding author)Email:

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Erin Nelson   (M.A., University of Waterloo) is a doctoral candidate in the Rural Studies Program of the School of Environmental Design and Rural Development at the University of Guelph, Ontario, Canada. Her research focuses on local organic food systems. Steffanie Scott   (PhD, University of British Colombia) is Assistant Professor in the Department of Geography and Environmental Management in the Faculty of Environment at the University of Waterloo, Ontario, Canada. Her current research focuses on rural development, small farmers, and the restructuring of local food systems. Judie Cukier   (PhD, University of Waterloo) is Associate Professor in the Department of Geography and Environmental Management in the Faculty of Environment at the University of Waterloo, Ontario, Canada. Her current research focuses on the impacts of tourism in developing countries. ángel Leyva Galán   (PhD, University of Leipzig) is Researcher and Professor at Cuba′s National Institute of Agricultural Sciences. His current work focuses on polyculture and the restoration of biodiversity in areas previously dedicated to monocrop sugar plantation.  相似文献   

Surface water seal application to minimize volatilization loss of methyl isothiocyanate from soil columns     

Catherine R Simpson  Shad D Nelson  Jerry E Stratmann  Husein A Ajwa 《Pest management science》2010,66(6):686-692

BACKGROUND: Metam‐sodium (MS, sodium methyldithiocarbamate) has been identified as a promising alternative chemical to replace methyl bromide (MeBr) in soil preplant fumigation. One degradation product of MS in soil is the volatile gas methyl isothiocyanate (MITC) which controls soilborne pests. Inconsistent results associated with MS usage indicate that there is a need to determine cultural practices that increase pest control efficacy. Sealing the soil surface with water after MS application may be a sound method to reduce volatilization loss of MITC from soils and increase the contact time necessary for MITC to control pests. The objective of this research was to develop a preliminary soil surface water application amount that would potentially inhibit the off‐gassing rate of MITC. RESULTS: Off‐gassing rate was consistently reduced with increasing water seal application. The application of a 2.5–3.8 cm water seal provided significantly lower (71–74% reduction in MITC volatilization) total fumigant loss compared with no water seal. The most favorable reduction in MITC off‐gassing was observed in the 2.5 cm water seal. CONCLUSION: This suggests that volatilization of MITC‐generating compounds can be highly suppressed using adequate surface irrigation following chemical application in this soil type (sandy clay loam), based on preliminary bench‐scale soil column studies. Copyright © 2010 Society of Chemical Industry  相似文献